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Primes of the form ((k+1)^k - 1)/k^2 = A060073(k+1).
4

%I #19 Jun 11 2021 09:45:18

%S 2,7,311,7563707819165039903

%N Primes of the form ((k+1)^k - 1)/k^2 = A060073(k+1).

%C Corresponding numbers k are listed in A127837.

%C Terms are the primes in A060073.

%C Next term has 15850 = 1 + floor((4357*log(4358) - 2*log(4357))/log(10)) digits and is too large to include. - _M. F. Hasler_, May 22 2007

%F a(n) = ((A127837(n) + 1)^A127837(n) - 1) / A127837(n)^2.

%t Select[Table[((n+1)^n-1)/n^2,{n,500}],PrimeQ] (* _Harvey P. Dale_, Apr 30 2011 *)

%o (PARI) A128466(n)=A060073(A127837(n)+1) /* see there. --- or: */ forprime(p=1,10^5,if(ispseudoprime(n=((p+1)^p-1)/p^2),print1(n,", "))); \\ _M. F. Hasler_, May 22 2007

%Y Cf. A127837, A037205, A060072, A060073, A058128, A128456

%K nonn

%O 1,1

%A _Alexander Adamchuk_, Mar 09 2007